1. Field of the Invention
The present invention relates to a multi-function actuator for performing both sound and vibration generating functions, and in particular, which can remarkably reduce vibration without influencing sound features in output of sound in the actuator.
2. Description of the Related Art
In general, a speaker is a sound generating apparatus which outputs an audible sound from an electrically or electronically received sound signal or a previously inputted bell or melody. Such speaker function has been adopted in mobile communication means such as a mobile telephone, however, causes noise in public places crowed with people. Thus, the speaker is restricted in use so as not to generate such noise. Instead, a vibration mode is frequently used for producing a call-incoming signal, and thus the necessity of a multi-function actuator is gradually increasing to meet such a function.
In the latest, accordingly, development has been actively made about the multi-function actuator which can faithfully perform basic functions while reducing the spatial size through integration of components such as a vibration motor, buzzer, receiver, speaker and the like.
However, the relative degradation of function is inevitably incurred in order to enable several functions, and accordingly various methods are being attempted to overcome the degradation. In particular, since a vibration function is executed by a vibration structure for generating vibration through resonance of a vibrator which is dependent from a spring, vibration is created even in output of sound.
Accordingly, the present invention is proposed to provide a multi-function actuator which has such a structure that can be used without great influence to sound and vibration output.
Hereinafter, detailed description will be made about the structure of a typical multi-function actuator of the prior art in reference to FIG. 1.
As shown in FIG. 1, the typical multi-function actuator comprises a case 10 with an internal space; a sound-generating diaphragm 1 with an outer end fixed to the upper end of the case 10; a voice coil 2 fixedly wound around the lower end of the diaphragm 1; a vertically magnetized magnet 4; an upper plate 3 attached to the magnet 4 for constituting a magnetic circuit; a yoke 5 for constituting the magnetic circuit together with the magnet 4; a weight 6 for constituting a vibrator body together with the upper plate 3 and the yoke 5; upper and lower suspension springs 7 and 8 for respectively supporting the vibrator body at upper and lower positions; and a vibrating coil 9 arranged on a grill 11 at the bottom of the case 10 for generating vibration.
The vibrating coil 9 is additionally provided as above so that a current is externally applied through lead lines 14 to 17. In this case, a method is adapted in which the four lines are connected to signal sources. Typically, the lines are connected to the signal sources designated as +, −, + and −.
Therefore, in the foregoing structure, when the current is applied through the lead lines 14 and 15, an electromagnetic force is generated to the voice coil 2 in the magnetic circuit constituted by the upper plate 3, the vertically magnetized magnet 4 and the yoke 5.
In other words, a magnetic field is produced to the voice coil 2 in the magnetic circuit constituted by the upper plate 3, the vertically magnetized magnet 4 and the yoke 5, in which a magnetic line from the N pole of the magnet 4 faces again to the S pole of the magnet through the upper plate 3, the voice coil 2 and the yoke 5 in sequence to produce the magnetic field. In this case, the voice coil 2 executes a speaker function by using a magnetic flux of the magnetic circuit due to the magnetic field.
Meanwhile, the yoke 5 is thinner in the lower part than in the side so that the magnetic flux partially leaks toward the vibrating coil 9 positioned at the bottom. The leaked magnetic flux incurs an electromagnetic force to the vibrating coil 9 when the current is applied through the lead lines 16 and 17.
In other words, the typical multi-function actuator in the prior art has the voice coil in a magnetic circuit unit at the diaphragm side so that the voice coil is applied with the signal when outputting sound. The lower magnetic circuit has the vibrating coil so that the lower coil is applied with the current when generating vibration.
In this case, in vibration of the multi-function actuator, the resonance frequency exists in the band of 100 to 200 Hz and the sound is outputted in the frequency band at least 350 Hz, and thus sound output can be considered regardless of vibration output due to the difference in band. However, since sound is obtained using an FM modulation mode in practice, sometimes the resonance frequency is simultaneously inputted in generating vibration different from the original intention so that the amount of vibration in the sound mode may be as large as in the vibration mode.